Agar-agar - made from algae - is always good for dessert. For the European readers (from planetkde.org), in case you don't know it yet, you can get this from most asian shops or order it online. A small package of 9 g agar powder should be enough for the whole family. Add slices of fruits, pour some milk and few drops of honey to taste. In hot days (like fews weeks ago in Germany), put some ice cubes. Enjoy!